As you round your lawn to mow the last stretch of grass, there’s an unbeatable sense of satisfaction from your work.
The scent of fresh-cut grass clippings is in the air, the sun is out, and there’s a refreshing drink waiting for you when you’re done…
There’s one problem: your lawn mower won’t stop.
First off: do not panic! There are several causes for this – maybe the switch stop didn’t connect, or the control cable isn’t working. Before you can diagnose the problem, you’ll need to shut down your mower.
How to turn off a lawn mower that won’t stop? You have several options:
- Use the kill switch
- Connect the switch stop tab
- Disconnect the spark plug
- Apply a full choke
- Switch off the gas
- Disconnect the power
Afterwards, you’ll need to do a maintenance check on your mower to identify the problem! Make sure the mower is fully switched off and cooled down before doing any work.
Why Won’t My Lawn Mower Turn Off?
If you’ve finished mowing but your lawn mower won’t turn off, there could be several causes. These can apply to anything from a self-propelled lawn mower to a ride-on model.
For those who use regular lawn mowing services, check in with them to make sure everything’s A-OK.
Always be mindful when inspecting lawn mowers – safety over everything!
Switch stop doesn’t make contact
This is a fairly common reason for a lawn mower failing to stop. For walk-behind mowers, you keep the blade control handle down when the mower is running.
However, sometimes when you release the handle, the lawn mower won’t stop. The switch stop at the end of the handle doesn’t make contact with the control bracket that “cuts off” the engine.
A likely cause is a hard bump or jostle while mowing, which knocked the parts out of place.
Faulty ignition switch
The ignition switch is central to controlling your mower’s engine.
If the switch is worn, damaged, or dirty, it cannot complete the circuit and thus won’t shut off the engine.
When your engine is running, the voltage jumps through your spark plug to create a spark. But when the wiring gains a direct ground path, the voltage gets sent to the ground instead.
Faulty or loose wiring means you don’t get that ground contact, so the lawn mower keeps running and doesn’t stop.
Malfunctioning control cable
This cable connects the handle to the ignition switch. When you engage the handle lever, it opens the switch, and vice versa.
If the cable has been damaged, snagged, or rusted, it might not function properly. It could fail to retract, keeping the ignition switch in the “on” position.
Some common scenarios include mowing around a stubborn bush or anything else that can snag the wire.
Malfunctioning engine brake
The brake of a small engine (such as those for a lawn mower) slows then stops engine function.
If the engine brake gets stuck in the wrong position, it could fail to stop the engine.
Clogged air filter
Dirty or clogged filters cause a gas mower to “run rich,” meaning there’s too much fuel and not enough air mixed in.
The engine might then misfire, stall, or even attempt to restart itself – and then fail to turn off.
It’s important to clean your lawn mower air filter regularly for maintenance.
How to Turn Off a Lawn Mower
It’s not always possible to diagnose the problem right away, especially with the engine still running.
So here’s how to stop a lawn mower that won’t turn off.
1. Use the kill switch
Most modern lawn mowers come with kill switches, which “kill” the engine in an emergency. Locate the kill switch and move it to the off position.
Other mowers – especially older ones – might not have a kill switch, so you may need to use one of the other methods.
2. Connect the switch stop tab
Consult your user manual for the location of the switch stop. Carefully open the engine cover, then use a screwdriver or pair of insulated pliers to bend the switch’s tab downwards.
Once the tab makes contact with the bracket, the engine should stop.
3. Disconnect the spark plug wire
If your mower doesn’t feature a kill switch, this is a DIY alternative. However, it’s crucial that you secure the mower to prevent it from moving towards you or someone else. Pointing it towards a wall is one workable strategy.
Do not just grab the wire to pull it out. This is very dangerous, especially if you have a pacemaker or cardiac issues.
Instead, use a pair of insulated pliers or a similar tool to pull out the spark plug wire.
NOTE: This is a good chance to see if you need to clean the spark plug or replace it entirely.
4. Apply a full choke
“Choking” the engine involves restricting the airflow, which causes the engine to stall. You can do this by holding the trigger down and revving the engine until it shuts off completely.
This won’t work if your mower has an auto-choke or primer built in, though. If that’s the case, you’ll need to choke the engine manually.
Remove the air filter, then use a rag to cover the carburetor to restrict air flow. Be very careful as you could injure yourself. Wear gloves to protect from burns!
NOTE: This could flood the engine with gas, so leave it to dry out for 30 minutes or so before starting the mower back up.
5. Switch off the gas
Before doing this, you’ll need to pull the throttle lever to “off” or turn the ignition key to “off.” This will ensure the engine isn’t active.
Alternatively, pull the bail lever towards the handle to deactivate the engine.
Locate the fuel valve or gas tap, which controls the fuel flowing from the tank to the carburetor. Turn the valve or tap to the off position, which cuts off the fuel supply.
The mower won’t stop immediately, since it needs to burn through the remaining fuel first. But once the fuel is gone, the engine will shut down.
If you can’t access the valve, an alternative is to pinch the gas line with pliers or similar tools.
6. Unplug the mower
In the case of an electric mower, simply disconnect the power cord. Be mindful when pulling so you don’t damage the plug or socket.
If you have a battery-powered mower, try to disconnect or remove the battery (aka the power source).
Checking Your Lawn Mower After It Stops
Once you’ve shut off the lawn mower and let it cool down, go over the different parts to see if you can find the break or fault.
It may be that there are multiple issues with your lawn mower – such as too much oil in the engine – that need addressing.
Some key components to check are the ignition switch, throttle cable, carburetor, and all the wiring. Exposure to the elements can cause connections and wires to degrade, which can interfere with function.
Make a list of anything that needs fixing or replacing so you can keep track! If the list starts getting too long, though, it might be time to let your old lawn partner retire – and start checking out the latest lawn mowers on the market for a new one.